J. Org. Chem. 1991,56,2045-2050 130.4, 129.6,128.6,125.8,80.2 (CZ), 55.6 (OCH3),28.8,15.5,8.1, 4.4; IR (film)u,, 1455,1082,750cm-';MS, m / z (70 eV), 174 (M+, 8),173 (121,158 (16), 149 (25), 143 (801,142 (100),141 (551, 129 (521, 128 (871, 127 (221, 116 (391, 115 (61); HRMS calcd for M+ 174.1045, obsd 174.1046. 1,6-Methano[ lO]annulene (1) enriched with 9% 13Cat the bridging carbon (Cll) was prepared from naphthalene according to the method of Vogel et al." but using 9% ['3C]chloroform during dichlormbene addition to 1,4,5,8tetrahydronaphthalene: mp 27 "C (lit." mp 27 "C); 'H NMR (400 MHz) 6 7.44 (m, 4 H), 7.1 (m, 4 H), -0.45 (t, JCH = 142.3 Hz, 2 H, H11); 13CNMR (100 MHz) 6 128.8, 126.2, 114.9 (C1 and 6), 34.9 (C 11, ca. 9-fold enrichment); IR (KBr) vu 1445,1397,1245,756 cm-'; MS, m/z (70 eV) 143 (12), 142 (M+,70), 141 (loo), 115 (33); HRMS calcd for ~3C112CloHlo 143.0816, obsd 143.0817. Generation and Quenching of Cations. Alcohols 4b and 6b (ca. 22 mg) were dissolved in either CHzClz(ca. 0.2 mL) or SOzCIF cooled to
